1. Field of the Invention
The present invention relates to staplers for stapling sheets of paper, sheets of corrugated cardboard, sheets of thin plywood, or the like, and staples used therein. In particular, the present invention relates to a stapler and a staple, by which a slip, a memorandum, or the like, can be temporarily fastened by the staple with ground paper, corrugated cardboard, or the like, so that the slip or the like can be easily unfastened without taking off the staple.
2. Description of the Prior Art
A stapler is widely used, for example, when a plurality of sheets are to be bundled up into an accumulation, or when a memorandum, a slip, or the like, carrying a list of received articles, a destination, etc., written thereon, is to be temporarily fastened onto a pasteboard, a corrugated cardboard, or the like. Taking into consideration capability of penetrating materials to be stapled, each of staples for use in such a stapler as described above is constituted by a wire-like linear body having a supporting portion and a pair of parallel stapling leg portions extending from the opposite ends of the supporting portion substantially perpendicularly thereto. The stapler is constituted by three members, that is, a base member having a matrix in which a bending groove for bending the stapling leg portions of a staple is formed, a staple supporting member accommodating staples and having a staple drive-out opening formed in opposition to the bending groove, and a pressing rotary member disposed behind the staple drive-out opening for pressing the staples toward the staple drive-out opening. These three members are pivotally supported at an end portion of the staple supporting member opposite to the staple drive-out opening. In general, the staples in the predetermined number are separably serially connected in the form of a bar of staples so that the bar of staples can be easily loaded in the staple supporting member. The bar of staples is pressed by the pressing rotary member toward the staple drive-out opening in the staple supporting member so that the forward one of the staples is always located at the staple drive-out opening.
In stapling, a stack of sheets of paper to be stapled is inserted between the matrix of the base member and the staple supporting member so as to bring a portion to be stapled of the stack of sheets into the position where the matrix and the staple drive-out opening are faced to each other, and the pressing rotary member is pressed down toward the base member. Then, the forward one of the staples is pinned into the stack of sheets through the staple drive-out opening. Thus, the forward free ends of the stapling leg portions of the driven staple pass through the stack of sheets to abut against the groove bottom of the bending groove in the matrix, and then bent by about 90 degrees along the shape of the groove bottom of the bending groove by the pressure exerted by the pressing rotary member so that the free ends of the stapling leg portions are pressed against the rear surface of the lowermost sheet. Accordingly, the supporting portion of the staple is pressed against the front surface of the uppermost sheet as well as the stapling leg portions thus bent are pressed against the rear surface of the lowermost sheet, so that the sheets in the given number can be stapled into an accumulation.
As described above, a plurality of sheets can be easily fastened through the staple of this type. Accordingly, the staple of this type is effectively used both in the case where a stack of sheets is stapled perpetually and in the case where a stack of sheets is stapled temporarily before the stack of sheets are regularly attached on another stack of sheets. In the latter case, it is necessary to unfasten the temporarily used staple. When, for example, the stack of sheets is thick, the staple can be easily unfastened from the thick stack of sheets while the stapling leg portions of the staple are opened by inserting a thin metal piece between the uppermost sheet and the supporting portion of the staple to pull up the supporting portion. In the case the stack of sheets is thin, on the contrary, not only the uppermost sheet but other sheets under the uppermost one may be broken when such a metal piece is inserted. Further, holes through which the stapling leg portions have been passed may be enlarged when the supporting portion of the staple is pulled up. It is therefore necessary to take an unfastening procedure in which the bent stapling leg portions are reformed linearly, and the stapling leg portions are pulled out from the supporting portion of the staple carefully.
In packing articles into a box, on the other hand, a mending tape or the like is used for temporarily fastening a memorandum or slip carrying a list of received articles, a destination, and the like, written thereon, onto the box. In the case where the box is formed of corrugated cardboard or in the case where the memorandum of slip should be used in the further, however, there is a possibility that the memorandum or the upper sheet of the corrugated cardboard may be broken when the mending tape is peeled off.